1. Field of the Invention
The present invention relates to communication terminal equipment and communication system incorporating the same and communication management method therefor. More particularly, the present invention relates to communication terminal equipment using a packet transmission network as a communication line and having a function capable of using services provided by a communication management terminal connected to the packet transmission network, to communication terminal equipment having a communication facility conforming to TTC JT-H323 standard and using packet transmission network as a communication line and having a function capable of using services provided by gatekeeper equipment connected to the packet transmission network, and to a communication system comprising a communication management terminal connected to a packet transmission network and a plurality of communication terminal equipment units using a packet transmission network as a communication line and having a function capable of using services provided by the communication management terminal and a communication management method for such a communication system.
2. Description of Related Art
As a communication system using a packet transmission network such as the Internet is a known communication system conforming to JT-H323 Standard provided by TTC (The Telecommunications Technology Committee, a Japanese standards committee) (hereinafter shall be referred to as TTC JT-H323 Standard).
This TTC JT-H323 Standard covers technical requirements for multimedia communication system in such packet networks that do not necessarily guarantee a quality of service.
As such packet networks are covered local area networks, corporate area networks, metropolitan area networks, intranets, and any interconnected networks including Internet.
In addition, PPP or other packet mode transmission by point-to-point connection or dial-up connection over GSTN (general switched telephone network) or ISDN (Integrated Service Digital Network) are also covered.
Further, these networks may consist of a single segment each, or may have such a complicated topology having a plurality of interconnected network segments.
The communication system subject to this TTC JT-H323 Standard includes one type embodied in such a manner that its call control is accomplished by applying gatekeeper equipment thereto.
Here, the gatekeeper equipment is defined as an end point in a network that provides real-time two-way communication between JT-H323 terminals on a packet network and between TTC terminals on a switched network or with other JT-H323 gateways. Also, other TTC terminals are defined as including those subject to JT-H310 (JT-H320 applied to B-ISDN), JT-H320 (ISDN), JTH321 (ATM), JT-H322 (a quality of service (QoS) guaranteed LAN), JT-H324 (GSTN), JT-H324M (mobile communications), and ITU-T recommendation V.70 (DSVD). Based on such a definition as above, VoIP (Voice over IP) telephone terminals are also put under control of gatekeeper equipment.
In this connection, the JT-H323 terminal is a communication terminal having a communication facility conforming to TTC JT-H323 Standard. Those terminals which are mentioned herein with a TTC standard number or an ITU-T recommendation number shall denote communication terminals or the like having a communication facility conforming to respectively corresponding TTC standards or ITU-T recommendations. For details of standards or recommendations referred to herein, reference should be made specifically to appropriate documents describing the same.
In JT-H323 terminal equipment using gatekeeper equipment, predetermined various kinds of information required for call control or the like functions are usually registered in such gatekeeper equipment. This registration in such JT-H323 terminal equipment is usually performed upon its start-up after power-on or when the predetermined various kinds of information were updated.
In the meantime, if JT-H323 terminal equipment has its power turned off before the predetermined various kinds of information after being updated are completely reregistered (registered again after deletion of the preceding information), occasionally the gatekeeper equipment may not allow such amended information to be registered upon start-up after next power-on, thus giving rise to an undesirable situation in which all communication via the gatekeeper equipment is disabled.
Accordingly, it is an object of the present invention to provide such communication terminal equipment, a communication system, and a communication management method that enable and ensure a proper function of communication using gatekeeper equipment.